Add support for special cases of scalar functions

[AnastasiiaSergienko]

Currently unsupported or partly supported scalar function:

String Functions:

• POSITION https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/position.htm#POSITION
• SUBSTR (partly supported without key words) https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/substr[ing].htm#SUBSTR[ING]
• TRIM (partly supported without key words) https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/trim.htm#TRIM

Date/Time Functions:

• ADD_ functions (can contain keywords, supported without them now)
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/add_days.htm#ADD_DAYS
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/add_hour.htm#ADD_HOUR
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/add_minutes.htm#ADD_MINUTES
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/add_months.htm#ADD_MONTHS
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/add_seconds.htm#ADD_SECONDS
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/add_weeks.htm#ADD_WEEKS
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/add_years.htm#ADD_YEARS

• CONVERT_TZ (can contain keywords, supported without them now)
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/convert_tz.htm#CONVERT_TZ

• DATE_TRUNC
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/date_trunc.htm#DATE_TRUNC

• DAY (can contain keywords, supported without them now)
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/day.htm#DAY

• _BETWEEN functions (can contain keywords, supported without them now)
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/days_between.htm#DAYS_BETWEEN
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/hours_between.htm#HOURS_BETWEEN
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/minutes_between.htm#MINUTES_BETWEEN
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/month_between.htm#MONTH_BETWEEN
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/seconds_between.htm#SECONDS_BETWEEN
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/years_between.htm#YEARS_BETWEEN

• EXTRACT
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/extract.htm#EXTRACT

• HOUR (can contain keywords, supported without them now)
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/hour.htm#HOUR

• MINUTE (can contain keywords, supported without them now)
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/minute.htm#MINUTE

• MONTH (can contain keywords, supported without them now)
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/month.htm#MONTH

• WEEK
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/week.htm#WEEK

• YEAR (can contain keywords, supported without them now)
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/year.htm#YEAR

• ROUND
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/round%20(datetime).htm#ROUND_(datetime)

• SECOND (can contain keywords, supported without them now)
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/second.htm#SECOND

Conversion Functions:

• CAST
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/cast.htm#CAST

• CONVERT
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/convert.htm#CONVERT

• TO_CHAR (datetime) (can contain keywords, supported without them now)
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/to_char%20(datetime).htm#TO_CHAR_(datetime)

Functions for Hierarchical Queries:

• CONNECT_BY_ISCYCLE, CONNECT_BY_ISLEAF, LEVEL, SYS_CONNECT_BY_PATH
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/sys_connect_by_path.htm#SYS_CONNECT_BY_PATH

Other Scalar Functions

• CASE
  https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/case.htm#CASE

• SPACE https://docs.exasol.com/sql_references/functions/alphabeticallistfunctions/space.htm#SPACE

We need to decide which of them we want to support and implement them if needed.

[redcatbear]

Shelved, because not in roadmap focus.